Interest at 1% per month (see items 2 and 5 below for exceptions for withholding taxes, and for motor vehicle fuel and intoxicating liquor floor taxes). (for example, secs. 66.0615(1m)(f)2, 71.55(6m), 71.61(3m), 71.67(2), 71.82(1)(a) and (c), 77.60(1), 77.76(1), 77.95, 77.982(2), 77.991(2), 78.68(1), 139.25(1), 139.44(9), 139.85(1), and 168.12(9), Wis. Stats. (2007-08).)
The interest of 1% per month is generally computed from the date the tax was originally due (for example, the unextended due date of the tax return) to the date the tax is paid, assuming the tax is paid before it becomes delinquent. If the department issues a notice of amount due because the additional taxes or excessive credits voluntarily disclosed are not paid at the time of the voluntary disclosure, interest of 1% per month is charged to the due date shown on the notice of amount due. For homestead and farmland preservation credits, interest is charged from the due date of the claim.
Note: If the department issues a notice of amount due because the additional taxes or excessive credits voluntarily disclosed are not paid at the time of the voluntary disclosure, and the amount due is not paid by the due date shown on the notice of amount due, "delinquent" interest of 1.5% per month will be charged from the due date shown on the notice of amount due to the date the amount is paid. (for example, secs. 66.0615(1m)(f)2, 71.55(6m), 71.61(3m), 71.67(2), 71.74(8), 71.82(2), 77.60(2), 77.76(1), 77.95, 77.982(2), 77.991(2), 78.68(2), 139.25(2), 139.44(11), 139.85(1), and 168.12(9), Wis. Stats. (2007-08).) The 6.5% ($35 minimum) delinquent tax collection fee will also be charged. (Section 73.03(33m), Wis. Stats. (2007-08).)
For income and franchise taxes and recycling surcharge, the interest for underpayment of estimated tax and estimated recycling surcharge. (Sections 71.84 and 77.947, Wis. Stats. (2007-08).)
Interest for underpayment of estimated tax and re-cycling surcharge may be waived if certain conditions are met, as provided in sec. 71.09(11), Wis. Stats. (2007-08), with respect to individuals, fiduciaries, partnerships, and limited liability companies; and in sec. 71.29(7), Wis. Stats. (2007-08), with respect to corporations.